1. Field of the Invention
This invention relates to sporting goods used in skiing. It is particularly directed to a ski binding operable to maintain a toe of a ski boot in association with a ski while permitting a heel of the ski boot to elevate with respect to a top surface of the ski.
2. State of the Art
Bindings for telemark skis and cross-country skis provide an interface between a ski boot and a ski that permits a skier to elevate the heel of a ski boot with respect to the top surface of the ski while skiing. Such bindings typically have a toe piece that holds a forward portion of a boot in pivoting relation to an axis disposed transverse to the ski. One such toe piece binding, which has become popular, is the 75 mm binding. The 75 mm binding has a toe piece which includes 3 retaining pins. The retaining pins fit into corresponding holes in the sole of the ski boot toe. A clamp mechanism holds an extended sole of the boot's toe in place over the retaining pins. While generally a very effective toe binding, the 75 mm binding undesirably permits a skier's heel significant freedom to slip laterally with respect to the ski.
A cable, or other linkage, extending from the binding toe piece for engagement with a heel portion of a ski boot has been used to increase heel stability in some cross-country type bindings. The linkage can hold the toe of a ski boot firmly in place in the toe piece. The cable or linkage typically locates a toggling heel piece in engagement with structure at the heel of a ski boot. In general, a skier must manually actuate the heel piece to engage a ski boot in the binding.
One commercially available cross-country binding is disclosed in U.S. Pat. No. 5,947,507 to Quintanna et al. The disclosed binding has an exposed spring located in front of a skier's foot, and a toe piece with a divided toe bar. The binding disclosed by Quintanna et al. also has an under-boot linkage to a heel piece arranged continuously to increase load on a boot toe with a corresponding increase in heel lift. The compression force applied, by the heel piece on the back of an installed ski boot in a heel-down position, is generated entirely by displacement of the toe spring as the heel lever is engaged.
A ski binding having a multileaved linkage between a toe piece and a heel retainer is disclosed by Bailey, in U.S. Pat. No. 4,887,833, issued Dec. 19, 1989. Bailey's disclosed binding includes an underfoot hinged rigid linkage to improve lateral stability of a ski boot with respect to the toe piece when the boot is in a raised-heel position. The linkage includes an anchor pivot axis and a single intermediate pivot axis disposed between a toe piece and a heel piece. The linkage further includes a pair of exposed compression springs disposed to provide a biasing force to urge a ski boot toe into engagement with the toe piece. No adjustment effective to accommodate different boot lengths without changing a compression of the exposed springs is illustrated.
A ski binding of a hybrid cross-country/alpine design and having spring elements mounted under a skier's foot is disclosed by Harold E. Ayliffe in application Ser. No. 09/997,842, published May 29, 2003. The disclosed binding has exposed springs carried by an underfoot carriage. The carriage is spaced from a toe piece by a plurality of cables arranged in an “X” pattern to provide enhanced stability of a skier's heel. A heel piece carried by the carriage is configured to provide step-in capability and a safety release. In use as an alpine binding, the carriage can be locked in place with respect to a ski to resist elevation of a skier's heel.
While certain available cross-country bindings are workable, it would be an improvement to provide a binding that is reliable, light in weight, and that better maintains a ski boot in lateral registration with a ski when the boot is in a heel-elevated position. Another advance would provide one or more pre-loaded spring assemblies to reduce a displacement distance required during assembly of a heel retainer onto a boot heel to generate a biased load effective to maintain a secure engagement between a boot toe and a toe piece of a binding. A further advance would provide a binding capable of accommodating displacement of a ski boot to a maximum heel-up position without fully compressing spring elements and thereby undesirably generating large spike loads between the binding components and the ski boot. A still further advance, for certain types of skiing, would provide a ski binding capable of providing significant and controlled loads on a ski boot effective to urge the ski boot heel from a heel-up position toward engagement with the top of the ski.